OICC Press Journal of Theoretical and Applied Physics 2251-7235 6 1 2023 11 17 Investigation of nitrogen plasma effect on the nonlinear optical properties of PMMA 10.1186/2251-7235-6-1 EN Davoud Dorranian Plasma Physics Research Centre, Science and Research Branch, Islamic Azad University, Tehran, Iran 0000-0001-8855-7425 Yasaman Golian Physics Department, Karaj Branch, Islamic Azad University, Karaj, Iran Alireza Hojabri Physics Department, Karaj Branch, Islamic Azad University, Karaj, Iran Journal Article 2023 11 17 Abstract Effects of low power direct current nitrogen plasma on linear and nonlinear optical properties of red BS dye-doped poly(methyl methacrylate) (PMMA) film are studied employing different optical techniques. From spectrometry data, it is shown that applying plasma in such a low range of power does not affect the linear absorption coefficient, linear refractive index, and optical bandgap of this dye-doped polymer; however, nonlinear parameters are changed. Experiments are performed using the second harmonic of a continuous Nd-Yag laser beam at a 532-nm wavelength and 20-mW power. The effect of nonlinear refractive index of red BS dye-doped PMMA film in broadening the laser beam is observed. The optical bleaching behavior is investigated by measurement of the intensity of laser beam through the sample. Its third-order nonlinearity is measured using close and open Z-scan data. Nonlinear absorption coefficient and refractive index, as well as real and imaginary parts of the third-order nonlinear optical susceptibility χ3, are changed significantly due to plasma treatment. PACS: 42.65.-k: 42.65.An: 42.70.Jk: 61.41. + e: 71.35.Cc.